The State Department confirmed Thursday that Nicaraguan authorities, with help from the United States, this month recovered a Soviet-era portable anti-aircraft missile that had apparently been put up for sale by black marketers. The United States has asked Nicaragua to investigate how the weapon got into unauthorized hands.

The United States is commending Nicaraguan officials for the successful recovery of the Russian-made SA-7 anti-aircraft missile, but also calling on authorities in Managua to investigate whether other missiles provided to that country during the Soviet era might be unsecured.

The comments follow a report by the Washington Times newspaper Thursday that Nicaraguan police, in an American-assisted "sting" operation, confiscated one of the deadly weapons that three Nicaraguans had tried to sell them.

According to the newspaper account, the black marketers were demanding several hundred thousand dollars for the missile and claimed to have several more.

The Washington Times said it was not known if the Nicaraguans had sold other SA-7s before being arrested.

It said the episode has "sounded alarm bells" in Washington, where U.S. officials have been openly concerned that portable air-defense missiles, the so-called "MANPADS" could be acquired by terrorists.

At a news briefing, State Department spokesman Richard Boucher provided few details of the case, but told reporters a missile was indeed recovered in a joint operation.

"We commend Nicaraguan authorities for successfully recovering one of their MANPADS, in this case a Russian-made SA-7, during a criminal investigation that culminated this month. Our Drug Enforcement Administration assisted them with that investigation," he said.

The SA-7 missile and launcher weigh less than 10 kilograms, have a range of almost 5000 meters, and are capable of bringing down a commercial airliner approaching or taking off from an airport.

Two SA-7s are believed to have been fired at an Israeli airliner leaving a Kenyan airport in 2002 but missed.

Nicaragua accumulated nearly two thousand of the missiles when the Marxist Sandinista movement was in power in the 1980s.

Spokesman Boucher said Nicaraguan President Enrique Bolanos gave assurances to President Bush and former Secretary of State Colin Powell in 2003 that his government would destroy all its remaining "MANPADS."

He said State Department arms-control officials would continue working with Nicaragua to assist in the process.

Mr. Boucher said the newly-revealed case suggests there might be a stockpile of unaccounted for missiles in the hands of the Nicaraguan military or other parties. He said the United States has asked the Managua government to investigate.

The Washington Times said U.S. officials suspect that those caught trying to sell the SA-7 this month are middlemen representing elements within the military who have a secret stash of the weapons.